bd-211: Remove deprecated rename functions from import_shared.go

- Removed renameImportedIssuePrefixes (wrapper, 3 LOC)
- Removed renameImportedIssuePrefixesOld (deprecated, 61 LOC)
- Removed replaceIDReferences (32 LOC)
- Removed replaceBoundaryAware (31 LOC)
- Removed isBoundary (5 LOC)
- Removed TestIsBoundary (37 LOC)
- Removed TestReplaceBoundaryAware (54 LOC)
- Total: 223 LOC removed (136 LOC code + 91 LOC tests)
- Active implementation is in internal/importer/importer.go
- All tests pass

cmd/bd/simple_helpers_test.go

@@ -45,59 +45,3 @@ func TestParseLabelArgs(t *testing.T) {
 		})
 	}
 }
-
-func TestReplaceBoundaryAware(t *testing.T) {
-	tests := []struct {
-		name     string
-		text     string
-		oldID    string
-		newID    string
-		expected string
-	}{
-		{
-			name:     "simple replacement",
-			text:     "See bd-1 for details",
-			oldID:    "bd-1",
-			newID:    "bd-100",
-			expected: "See bd-100 for details",
-		},
-		{
-			name:     "multiple occurrences",
-			text:     "bd-1 relates to bd-1",
-			oldID:    "bd-1",
-			newID:    "bd-999",
-			expected: "bd-999 relates to bd-999",
-		},
-		{
-			name:     "no match",
-			text:     "See bd-2 for details",
-			oldID:    "bd-1",
-			newID:    "bd-100",
-			expected: "See bd-2 for details",
-		},
-		{
-			name:     "boundary awareness - don't replace partial match",
-			text:     "bd-1000 is different from bd-100",
-			oldID:    "bd-100",
-			newID:    "bd-999",
-			expected: "bd-1000 is different from bd-999",
-		},
-		{
-			name:     "in parentheses",
-			text:     "Related issue (bd-42)",
-			oldID:    "bd-42",
-			newID:    "bd-1",
-			expected: "Related issue (bd-1)",
-		},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			result := replaceBoundaryAware(tt.text, tt.oldID, tt.newID)
-			if result != tt.expected {
-				t.Errorf("replaceBoundaryAware(%q, %q, %q) = %q, want %q",
-					tt.text, tt.oldID, tt.newID, result, tt.expected)
-			}
-		})
-	}
-}